mtv wrote:Battson,

To (hopefully) return this thread to your specific question, before I purchased a composite prop, I did some research on that flavor of props.

One gent I spoke to was the Director of Maintenance of an air carrier that was operating Beech 1900 aircraft off gravel runways regularly. These aircraft were all equipped with composite props. And those props were driven by fairly powerful turbines. He said before they figured out that turning off the nose wheel power steering would reduce rock damage to the props, they experienced frequent rock chips to the face of the blades.

The "fix" they used was "application of Marine Tex or other high quality epoxy coating" to repair those dings. He said turning off the power steering reduced the frequency of rock dings, but they still got many. He said they'd been using this procedure for some time with no issues, and it was approved by yhe manufacturer (this was a 121 operator).

The idea was to reseal the chip so that moisture couldn't seep into the wood core of the prop. Sorry, but I can't recall the manufacturer of the prop....but it wasn't MT.

I've used epoxy material to reseal rock chips on composite props, and seems to work fine.

One of the significant advantages of composite props is that if you're operating on gravel or worse, sand, there is virtually no erosion or damage to leading edges, unlike aluminum props, where you're constantly filing off $$$$ worth of leading edge,till you have a toothpick left. The same goes for props used on seaplanes and ski planes, where leading edge erosion can be substantial. The composite props have a hard steel leading edge which absorbs those rock dings with minimal damage.

I have run several composite props in both recreational flying and commercial ops, and I love them, fwiw. Of course, I got them all for free, otherwise, I'd have hated them.......

MTV

fiftynineSC wrote:Things are rarely binary. Composite props have been "the standard" in other types of flying for years now. No reason they have to be "good" or "bad" in our application......everything has trade offs. I've seen the repairs on MT props (no experience with trail blazers) and they don't seem to be an issue. Very conventional materials and long history in other industries fixing minor blemishes in epoxy. My mechanic maintains several and he has no fears or qualms about them.

Making the argument about rocks and abrasion is one thing (surely debatable)...but saying or making the argument as some have made in other threads/forums that "they won't work" on our planes is just wrong. Go to an aerobatic competition on a weekend; they are hanging on the front end of 540's spinning at 2800 RPM exposed to radical gyroscopic forces every day. If it was a major problem they'd be grounded or their would at least be an AD. Composite props dominate that market.

59SC

AK-HUNT wrote:

Battson wrote:Hi everyone,

We find ourselves upgrading propellers, a nice position to be in! We are considering moving to composite instead of the ol' Black Mac.
We're sticking with a long two bladed prop, probably an MT or Hartzell Trailblazer.

A question about composite props - how easy are they to repair when minor stone chips appear in the aft face of the blades?

We had quite a bit of gravel rash on our old McCauley, on the aft face of the blades.
I wondered how the MT or Trailblazer will hold up to this kind of wear and tear?

All opinions and thoughts are encouraged! I want to hear those bad experiences as well as the good.

Battson

When I was on the verge of buying an MT, a local shop had one removed < 50 hrs having to go back to MT for a rock ding in the face. That was enough for me to stay with the Mac. A couple days not operating during my busy season would be a killer. There have been several other smoked MT's around here (theres a thread with pictures on the sky wagon Facebook....well there WAS anyway).

A local operation that runs one on their float plane seem to love it. If I were primarily on floats I'd do it or if the off-road stuff was a little tamer.
Weight/thrust/etc is honestly secondary to reliability for me....and most guys don't have huge repercussions by being grounded for a day or 2.

All this stuff is just tools. One tire/prop/rear seat/etc etc etc isn't "the best" for all operations IMO. Use whats best for you, but if you are getting mid cord dings, ya might look closely at the repair criteria. Could have changed. It doesn't help that when someone does bring up negatives of an MT they kinda get dogpiled. Makes it a polarizing issue (as u see above) and that doesn't help anyone.

Cheers,
KA

Barnstormer wrote:Jon,
I have a Whrilwind on the SQ2. You've seen my videos so know what I flown on and off. When I was in Texas I could only fly off fine grain beach type sand with just a couple of times on the type of shale like what's at Skalywag's place. The prop was in pristine condition when I fly up here to Alaska. Nearly 300 hours last year in the aforementioned places you've seen in the videos. By seasons end there were hundreds of chips on the back side of the blades. Two on the front one of which was to the weave. I epoxied those two. I sent the blades back to Whirlwind for complete reconditioning/repainting at the cost of just over a grand (I was more concerned about some spider cracks in the "gel coat" near the root of the blades that ended up being just cosmetic).

I have no idea how a metal blade would have held up. I figure this is just the cost of doing the flying I do. BTW the prop has a nickel leading edge, I'm told far superior to a steel leading edge.

PAMR MX wrote:The performance is great on the couple I'm around but that's it imo.

Minor face damage is extremely easy to repair. I simple dab of over the counter 5 min epoxy is all that is recommended. It can then be sanded smooth and painted. Deeper damage can be repaired as well and is fairly simple.

1. The whole prop has a coating of bondo that will develop cracks over time and look ugly. Manufacturer says it's airworthy but it's ugly.

2. Minor blade strikes that could be filed out and flown home on a metal prop destroy the mt. When a composite structure fails it fails catastrophically.
3. Minor dents in the leading edge all tho small in size and airworthy in size can delaminate the erosion sheath to an unairworthy amount.
4. I have had a rock completely penetrate the face of the prop to the other side.
5. They can be locally overhauled but the blades typically have to be shipped to Germany for repair. Exchange sets are available but not cheap.
Thanks MX - that is exactly the kind of operational experience I wanted to hear!



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motoadve wrote:I like the MT a lot, had mine for 1200hrs so far, 1 small nick, very easy to repair.
Epoxy, sand it and you are good to go.

Mine is on a 182 flying lots of backcountry, its durable in my opinion.

I do think they do give a real advantage for the backcoutry by being light, wide (its like an air brake) you also get quick throttle response .

North River wrote:My experience with MT’s, take it for what its worth.

180hp Supercub on 31s summer and wheel skis winter 2-blade MT. Good – fast cruise, smooth running. Bad – one rock ding from taxying on maintained gravel runway meant replacement of blade and downtime. It was a bad ding. Takeoff and climb performance nothing special, but not terrible either.

180hp Scout on floats 2-blade MT. Good – smooth, no unrepairable water erosion. Bad – water erosion ate paint off leading edge behind stainless steel. Not a big deal but looked bad and required upkeep to make sure the composite wasn’t becoming compromised. Takeoff and climb performance not impressive, but a lot of that is from big draggy floats.

285hp 180 on bushwheels, 2-blade MT. Good – smooth operation, fast cruise, lightweight. Bad – takeoff performance fine but nothing special. One rock ding from gravel bar smashed stainless steel leading edge in. Factory says its ok and owner still flying it so I guess its ok, just looks bad with a big ol bulge in leading edge.

300hp 185 on floats 3-blade MT. Good – lightweight for 3 blade, smooth running, good takeoff performance, no water erosion on second prop. Bad – first prop had bad water erosion behind ss leading edge within 100hrs. chipped paint and composite to the point was worried about moisture getting into the core. It was completely repairable, but when the trailing edge started to separate we traded it in for a new nickel leading edge prop. This one has held up great so far (1 year, 300ish hrs). Neither good nor bad – thoughts on performance: this prop replaced a 2-bladed 86in Mac that was recently OH but shook pretty good. The change to the MT made a HUGE difference in vibration, now its butter smooth. Takeoff performance is a bit better off the water, especially with a load. I do not feel it pulls quite as hard as the 3-blade Black Mac, but this is purely speculative as I have not done back to back tests. But after flying a bunch of different float planes you do develop a sense of it. FWIW

I have considered trying an MT on my pet wheel 180 with 275hp Pponk. The reason I haven’t yet is the lack of gain for $10k additional. The two-blade 86in Mac is smooth on this plane, relatively lightweight, and will pull any load I can land with out of the same spot so performance is good. Additionally, as a commercial plane the risk of having down time due to rock damage is too high. The MT with the nickel edge MIGHT handle it just fine. But I already know the Mac does. But the 3 blade MT would look so much cooler……

Squash wrote:I have about 500 hours on two MT propellers. One is a 2-blade on the Husky and one is a 3-blade on the 185. So far, I have not made any significant repairs to the blades. The leading edges look brand new. I did have a small ding in the steel leading edge of my husky prop before I had nickel leading edges added during an overhaul.

This in contrast to my two aluminum propellers that I ran prior to the MT props. They had dings in the leading edges that I couldn't get out completely and the filed leading edges looked bad.

The documents that came with my MT prop included a manual for repairs. I looked on the website but cannot find it there. I'm surprised no one has posted a copy of this manual because it shows how much damage can be repaired and it's surprising how much you can repair these props. Some of the photos show chunks way larger than I would feel comfortable having my mechanic deal with. The bottom line is that these blades can go a long way and can be repaired significantly.

I'm not sure I agree with "you either love or hate these props". Why so polarized? ..... But so far I love my props

Rob wrote:Hi Battson,
I still have not made the Chamois pursuit

Before I venture down a longwinded Rabbit hole, let me just put it out there, there are currently NO composite props that meet the criteria of your first post. No one, is currently making a Long, 2 bladed, constant speed, composite propellor for the big 6's. Craig Catto is making some dandy, long, fixed pitch, 4 cyl choices, but no one is currently making anything that will dethrone a 88"-90" C66 in the missions it shines in. And that propellor doesn’t work for you….

All of the props in your OP will take Superficial, Smooth stone chips just fine. The Aluminum props will just see dings, and lose paint or a touch of metal. The composite props will lose a touch of paint, and probably gain a couple little ugly epoxy patches which can be color matched if you feel so inclined.

Having said that I urge you to not make a purchase based on that single piece of knowledge. After all, buying a $10K-$20K propellor, is a substantial investment, (no matter what your bank account looks like) and more importantly, as Skaly and Slohawk note, a poor choice can leave your $200k bird ground bound, for extended stays.

Things I would urge you to evaluate would be;

1) First and as always, most importantly, Mission, mission, mission.... sounding like a broken record here, but as obvious as it is, if you elect to choose the softest tire on the market, you should have no gripes when it gets cut like soft butter with a hot knife, when it sees shale... choosing the lightest weighing prop can yield similar results. Will the mission need the weight loss more than the robustness? Some spell lightweight W-E-A-K.... in this application, I concur. (But two of my airplanes are still wearing a light weight props )

2) TBO's.... TBO's are like paychecks. Good bad or indifferent, It's how society has elected to judge a component's net worth. Electing to follow a TBO may a purely personal choice (for some), but as a general rule a component with a shorter TBO, has a shorter TBO for a reason, putting your head in the sand will not make that reason go away

3) Repair / service manuals.... A comprehensive, and open minded look in the manuals the most revered props on this website, will shed far more light that anyones opinion. There ways we simply must maintain these propellors. The books will tell you that information, the salesmen will not, the guy who really wants to believe his $20K investment is superior to others probably won't. In fact he probably hasn't gone down that rabbit hole himself

4) Customer service.... and not from the sales department! Selling $20K props has made them good at making you feel good. Poll the people who have had catastrophic failures, and how they were treated afterwards, because that relationship is likely to be far more important to your continued happiness with a product than the one that is forgotten shortly after you hand over your hard earned cash.

5) The BIG damage repairs. You wouldn't select a bush beater airplane solely on how well the grease wipes off the belly, don't pick a propellor sole on how it sheds superficial stone damage. Ask how it takes a stop sign, because it's the big damage that's going to leave you parked on a mountain side, not missing paint or dings. You are not buying a small disc'd prop meant to go on the nose of a lightweight acro buzzer, nearest I can tell for your mission, you are buying a giant weed wacker / stickball bat.

Anyways.. these are just some thoughts regarding props in general that anyone should consider. As luck would have it, I also have a bit of Mac (dozens) and MT (only 3) experience, some good, some bad (with both flavors). I can share some of that experience on another post, this afternoon. Skaly's initial post and MT experience does not surprise me in the least bit, nor does G44's. I know people that love them, I know people that hate them. All the reasons above and a few more (not another posters opinion) will determine which category you fall in. For my money MT’s in specific are just like any other prop out there, full of compromises... and merits

Take care, Rob

175 magnum wrote:On the IVO prop the recommended repair for chips is to use a mix of CrazyGlue and baking soda. It works great. The Bearhawk has the 4blade prop and does serious off-road stuff and has never had any serious problems.

PAMR MX wrote:The performance is great on the couple I'm around but that's it imo.

Minor face damage is extremely easy to repair. I simple dab of over the counter 5 min epoxy is all that is recommended. It can then be sanded smooth and painted. Deeper damage can be repaired as well and is fairly simple.

1. The whole prop has a coating of bondo that will develop cracks over time and look ugly. Manufacturer says it's airworthy but it's ugly.

2. Minor blade strikes that could be filed out and flown home on a metal prop destroy the mt. When a composite structure fails it fails catastrophically.
3. Minor dents in the leading edge all tho small in size and airworthy in size can delaminate the erosion sheath to an unairworthy amount.
4. I have had a rock completely penetrate the face of the prop to the other side.
5. They can be locally overhauled but the blades typically have to be shipped to Germany for repair. Exchange sets are available but not cheap.



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